Came out to perform preventative maintenance on furnace. Discussed with customer about maintenance being provided, filters, and any issues that they might be experiencing. Customer stated that he is unsure if the filters need to be replaced, but does know that they were changed right before they moved in at the end of November. Inspected filters and they were still good. I did, however, find the returns caked in dust/debris. The home was repainted and stuff inside and I’m not sure if the system was filtered at the time. Made customer aware of it. Inspected the blower assembly, motor, electrical components, heating components, heat exchanger and evaporator coil. Heat exchanger integrity is still good. Found the dust and debris had made its way to the blower assembly, but the evaporator coil didn’t have much on it. Let customer know that the blower assembly and ductwork should be cleaned. Cleaned flame sensor and dust off the burners and components. Checked system operation, amps, temper